Polyolefin Laminate Structure for Damp-Heat Barrier Adhesion
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Solution Overview
Problem
Conventional laminates with polyolefin substrates face issues of insufficient adhesiveness and damp heat resistance, leading to potential damage to the inorganic vapor deposition layer due to thermal expansion of the substrate in damp heat environments.
Innovation Solution
A laminate structure comprising a polyolefin substrate, a polyurethane layer with a thermal expansion coefficient of 150×10^-5 K^-1 or less, and an inorganic vapor deposition layer, where the polyurethane layer is formed from a polyurethane resin containing specific components such as alicyclic polyisocyanate, high molecular weight polyester polyol, and a cross-linking agent, enhancing adhesiveness and damp heat resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a polyolefin substrate is used, then the substrate provides good chemical resistance and durability, but the adhesiveness between the substrate and gas barrier coating material is insufficient
Solution Approach 1:
An anchor coat layer made of polyurethane resin is introduced as an intermediary between the polyolefin substrate and the gas barrier coating material. This anchor coat layer serves as a mediator that provides both adhesion to the substrate and compatibility with the coating material, resolving the adhesion issue while preserving the substrate's chemical resistance
Solution Approach 2:
The invention uses a composite structure combining polyolefin substrate, polyurethane anchor coat layer, and gas barrier coating material. Each layer contributes its specific properties: the polyolefin provides chemical resistance, the polyurethane provides adhesion, and the coating material provides gas barrier functionality
2Reliability
If the substrate contains polyolefin resin, then the substrate is cost-effective and durable, but the substrate thermally expands in damp heat environment causing damage to the inorganic vapor deposition layer
Solution Approach 1:
The invention controls the thermal expansion coefficient of the polyurethane anchor coat layer to be 150×10^-6/K or less, matching it closely with the polyolefin substrate's thermal expansion characteristics. This parameter control prevents differential thermal expansion stress that would otherwise damage the vapor deposition layer during damp heat treatment
Solution Approach 2:
The invention specifically addresses thermal expansion mismatch by selecting and formulating the polyurethane resin to have a thermal expansion coefficient that closely matches the polyolefin substrate. This minimizes expansion differential stress on the brittle inorganic vapor deposition layer during temperature cycling
3Ease of operation
If the gas barrier coating material and inorganic vapor deposition layer conform with substrate expansion, then the laminate maintains flexibility, but the inorganic vapor deposition layer becomes damaged
Solution Approach 1:
By controlling the thermal expansion coefficient of the polyurethane anchor coat layer to be 150×10^-6/K or less, the invention minimizes the differential expansion between layers. This parameter control allows the laminate to maintain flexibility while preventing stress concentration that would cause cracking of the vapor deposition layer
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The laminate exhibits excellent adhesiveness and damp heat resistance, preventing damage to the inorganic vapor deposition layer by suppressing thermal expansion of the polyolefin substrate.
Implementation Method 1
the substrate may thermally expand in a damp heat (retort) environment. In such a case, the gas barrier coating material and the inorganic vapor deposition layer may conform with the expansion of the substrate, and the inorganic vapor deposition layer may be damaged
Implementation Method 2
an inorganic vapor deposition layer disposed on the one-side surface of the anchor coat layer
Data Source
Figure 1~2
AI summary
A laminate 1 includes a polyolefin substrate 2, a polyurethane layer 3 disposed on the polyolefin substrate 2, and an inorganic vapor deposition layer 4 disposed on the polyurethane layer 3. A thermal expansion coefficient of the polyurethane layer 3, which is measured in a temperature range of 90°C to 120°C, is 150 × 10-5K-1 or less.